Simultaneous pyrolysis and communition for fuel flexible gasification and pyrolysis

ABSTRACT

A biomass thermal conversion system including a fixed bed drying zone; a fixed bed pyrolysis zone fluidly connected to the drying zone; a combustion zone fluidly connected to the pyrolysis zone by a material path; and a comminution mechanism arranged across the material path between the pyrolysis zone and the combustion zone, configured to grind char off a pyrolyzed surface of solid biomass and reduce a dimension of the solid biomass below a threshold size.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/790,332 filed 15 Mar. 2013, which is incorporated in its entirety bythis reference. This application is related to U.S. application Ser. No.14/216,206 filed 17 Mar. 2014, which is incorporated in its entirety bythis reference.

TECHNICAL FIELD

This invention relates generally to the field of biomass thermalconversion, and more specifically to a new and useful communition methodfor gasification or pyrolysis machines.

BACKGROUND

Biomass thermal conversion is an attractive method for generatingsynthetic gas to run engines or to produce useful end products such ascharcoal. Carbonaceous byproducts are typically inexpensive or free tosource. Unfortunately, biomass byproducts come in a wide array of shapesand sizes, and extra machinery is usually required to pre-process thefeedstock into forms acceptable to gasification or pyrolysis machines.This processing equipment is often expensive and difficult to operate,which challenges the ultimate attractiveness of biomass thermalconversion solutions.

Thus, there is a need in the field of biomass thermal conversion forsystem capable of utilizing a wide range of fuel shapes and sizes,without feedstock preprocessing on the front end. This inventionprovides such a solution through a novel “reactor-internal” fuelprocessing solution that reduces a wide range of input biomass feedstockto a common size of granulated char.

BRIEF DESCRIPTION OF THE FIGS.

FIG. 1 is a variation of a horizontal pyrolysis retort with the chargrinder.

FIG. 2 is a variation of a slanted pyrolysis retort with the chargrinder.

FIG. 3 is a variation of a hybrid fixed kinetic bed gasifier with thechar grinder.

FIG. 4 is a variation of a cyclonic hybrid fixed kinetic bed gasifierwith the char grinder.

FIG. 5 is a variation of a cyclonic hybrid fixed kinetic bed gasifierwith the char grinder enabling indirect gasification.

FIG. 6 is a sectional view of a variation of the char grinder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments of the inventionis not intended to limit the invention to these preferred embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

1. Gasifier with Char Grinder

As shown in FIG. 1, the biomass thermal conversion system 10 includes adrying zone 200, a pyrolysis zone 300, a combustion zone 400, and a chargrinder 100. The char grinder 100 (comminution mechanism) preferablyincludes a body 110 and an abrading cage 130 in translational relationwith the body 110, as shown in FIG. 6. This biomass thermal conversionsystem 10 functions to introduce communition (e.g., granulation) as aconcurrent, integrated, in-situ component of the pyrolysis process, suchthat granular biomass having a substantially uniform form factor can beoutput into subsequent gasification stages or charcoal removal systemsdespite biomass input having a variety of non-uniform shapes and sizes.

The biomass thermal conversion system 10 can be a gasifier, wherein thegasifier can additionally include a reduction zone 500. The char grinder100 is preferably arranged along the material flow path between thepyrolysis zone 300 and the combustion or reduction zone 500 (e.g., asshown in FIG. 3). The gasifier is preferably utilized within a powergeneration system that converts gaseous fuel (e.g., syngas) produced bythe gasifier into electric power (e.g., with an engine and alternatorsystem), but can alternatively be utilized within a system that extractsbiochar, pyrolysis oil, or any other suitable product. Alternatively,the biomass thermal conversion system 10 can be a pyrolysis retort witha char grinder 100 arranged along the combustor (e.g., as shown in FIGS.1 and 2), or can be any other suitable biomass thermal conversion system10.

Simultaneous pyrolysis and comminution of biomass confers severalbenefits over other material reduction methods. First, comminution ofthe biomass within the pyrolysis phase enables low-energy size reductionof the biomass feedstock. This is due to the inventors' discovery thatraw biomass is an order of magnitude stronger than made and cooledcharcoal, and that cold charcoal is another order of magnitude strongerand more energy intensive to fragment than hot charcoal at pyrolysistemperatures. Thus, placement of the char grinder 100 in or immediatelyafter the pyrolysis zone 300 allows for sufficient char granulation witha significantly smaller amount of energy input than grinding theunprocessed biomass prior to reactor entry or grinding the charcoalafter cooling (e.g., after exiting from the reactor). This discoveryallows for low-energy comminution methods to be used in lieu of thehigh-energy methods used in conventional systems. More specifically,abrasion (e.g., leveraging friction between the biomass particle and anabrading surface) can be used instead of conventional cutting methods.Not only does this reduce the requisite energy input into the system,but this also reduces the need and maintenance of sharp cutting tools,as abrasion can be accomplished with dull components. Furthermore, theuse of abrasion to comminute the char reduces the complexity of themachinery.

Second, the inventors have discovered that grinding during pyrolysisresults in more uniform pyrolysis of the biomass and allows for lowerpyrolysis temperatures to be used, and/or less heat energy input. Duringconventional pyrolysis, a thermally insulative layer of char forms onthe biomass exterior, which typically slows further pyrolysis of thebiomass interior. The grinding effectively removes the thermallyinsulative layer of char as it forms, continually exposing raw biomassto the pyrolysis heat. The result is a more consistent pyrolysistemperature throughout the material and the pyrolysis bed, substantiallyeliminating localized areas of high or low temperatures, which lead tovariability in the made char and/or tar gas characteristics.Additionally, removing the insulative char layer as it forms can resultin significant reductions in pyrolysis time, especially with large chunkfuels such as logs and construction debris.

The drying zone 200 of the biomass thermal conversion unit 10 functionsto receive and dry wet biomass. The drying zone 200 is preferably afixed bed to minimize energy expense, but can alternatively be a kineticbed. The drying zone 200 is preferably fluidly connected to thepyrolysis zone 300, wherein dried biomass is preferably passed to thepyrolysis zone 300. The drying zone 200 can be fluidly connected to thepyrolysis zone 300 by a material transporter that moves dried biomassfrom the drying zone 200 to the pyrolysis zone 300, or can be arrangedabove the pyrolysis zone 300, wherein gravity preferably moves driedbiomass from the drying zone 200 to the pyrolysis zone 300. The dryingzone 200 is preferably a substantially continuous bed with the pyrolysiszone 300 (e.g., coaxially arranged with the pyrolysis zone 300), but canalternatively be a separate bed from the pyrolysis zone 300, wherein thedrying zone 200 is preferably offset from the pyrolysis zone 300 suchthat material transfer between the zones can be controlled. The dryingzone 200 is preferably heated by waste heat from the pyrolysis zone 300,but can alternatively be heated by waste heat from the combustion zone400, the reduction zone 500, the gaseous fuel, the power generationsystem (e.g., engine exhaust or radiator), or by any suitable wasteheat. When the drying zone 200 is heated by waste heat from thereduction zone 500, gaseous fuel, or power generation system, a portionof the waste heat is preferably removed to maintain the drying zonetemperature under pyrolysis temperatures. The drying zone 200 preferablyincludes a biomass inlet 210 that receives wet biomass, wherein thebiomass inlet 210 is preferably controlled and maintains a fluidimpermeable seal within the gasifier. The biomass inlet 210 can includean airlock (e.g., a rotary airlock), a vent, a sealable lid, or anyother suitable mechanism that permits material transfer therethroughwhile maintaining a substantially fluid impermeable seal. However, thebiomass inlet 210 can be substantially open to the ambient environment.

The pyrolysis zone 300 of the biomass thermal conversion system 10functions to pyrolyze dried biomass. The pyrolysis zone 300 ispreferably a fixed bed to minimize energy expense, but can alternativelybe a kinetic bed. The pyrolysis zone 300 is preferably fluidly connectedto the drying zone 200 and combustion zone 400, wherein dried biomass ispreferably passed to the pyrolysis zone 300 from the drying zone 200 andtar gasses are preferably passed to the combustion zone 400 from thepyrolysis zone 300. Char can additionally be passed to the combustionzone 400 from the pyrolysis zone 300. The pyrolysis zone 300, or aportion thereof, is preferably arranged above the combustion zone 400 toleverage gravity in the transfer of char to the combustion zone 400, butcan alternatively be arranged adjacent or below the combustion zone 400,wherein a material transporter (e.g., an auger) preferably movesmaterial from the pyrolysis zone 300 to the combustion zone 400.However, the pyrolysis zone 300 can be otherwise arranged. The pyrolysiszone 300 can additionally include a pyrolysis transporter (e.g., anauger) that controls material transfer through the pyrolysis zone 300,but material flow through the pyrolysis zone 300 is preferably passive,wherein the consumption of pyrolysis products by the combustion zone 400and/or reduction zone 500 preferably move biomass through the pyrolysiszone 300. The pyrolysis zone 300 is preferably heated by waste heat fromthe combustion zone 400, but can alternatively be heated by waste heatfrom the reduction zone 500, by waste heat from the gaseous fuel, fromwaste heat from the power generation system (e.g., engine exhaust orradiator), by a heater, or by any suitable heat.

The combustion zone 400 of the biomass thermal conversion system 10functions to combust the tar gasses produced from pyrolysis of thebiomass. The combustion zone 400 is preferably an open combustionvolume, with full mixing of tar gas and air. Alternatively, when tar gascombustion is combined with the char bed, the combustion zone 400 ispreferably a kinetic bed to maximize air and tar gas mixing, but canalternatively be a fixed bed or any other suitable char bedconfiguration. The combustion zone 400 is preferably fluidly connectedto the pyrolysis zone 300, wherein tar gas preferably flows to thecombustion zone 400 from the pyrolysis zone 300. The combustion zone 400can additionally be fluidly connected to a reaction zone, whereincracked tar gasses preferably flow to the reduction zone 500 from thecombustion zone 400. Char can additionally be passed to the reductionzone 500 from the combustion zone 400, but can alternatively be passeddirectly from the pyrolysis zone 300 to the reduction zone 500.Alternatively, char (e.g., comminuted char) can be removed from themachine and not subjected to further reaction, such as when charcoal asan output product (e.g., biochar) is desired. The combustion zone 400can be substantially continuous with the pyrolysis zone 300, wherein airand heat are directly introduced into a portion of the pyrolysis zone300 to combust the tar gasses in said pyrolysis zone 300 portion.Alternatively, the combustion zone 400 can be substantially separatedfrom the pyrolysis zone 300 wherein the char of the pyrolysis zone 300is preferably isolated from the combustion zone 400 by a separatechamber. The combustion zone 400, or a portion thereof, is preferablyarranged within or above the pyrolysis zone 300, but can alternativelybe arranged below or adjacent the pyrolysis zone 300, wherein thenegative pressure (suction) created by the combustion of tar gassespulls uncombusted tar gasses and/or char from the pyrolysis zone 300.

The combustion zone 400 preferably includes an air manifold 410 thatintroduces an oxygen-containing gas into the combustion zone 400, and aburner 800 that combusts the tar gas and oxygen within the combustionzone 400. The combustion zone 400 is preferably defined at the outlet ofthe air manifold 410 within the system. The air outlet can be an openingin a wall of the system, be a nozzle that extends into the system, or beany other suitable air outlet. The air manifold 410 is preferablyfluidly connected to an oxygen source at an air inlet 411. The airmanifold 410 preferably extends through and is heated by a reactionphase (e.g., the reduction zone 500, the interface between the reductionzone 500 and the drying zone 200, the gas outlet, etc.), but canalternatively extend directly into the combustion zone 400. The airmanifold 410 can function to reduce the amount of heat transferred tothe drying zone 200, wherein the air manifold 410 extends along theinterface between the drying zone 200 and the heat source for the dryingzone 200. The air manifold 410 preferably introduces air into thecombustion zone 400 such that air flows in a substantially linear pathfrom the combustion zone 400 to the gas outlet (e.g., directly or thoughthrough a reduction zone 500), but can alternatively introduce air intothe combustion zone 400 such that a rotational/circular airflow patternis formed within the combustion zone 400. The air manifold 410preferably directs air toward the gas outlet, but can alternativelydirect air away from the gas outlet, wherein the air is turned anddirected by a casing end or fixed bed (e.g., of the pyrolysis zone 300)toward the gas outlet (e.g., into the reduction zone 500). The burner800 functions to heat the combustion zone 400 to the combustiontemperatures. The burner 800 can be a flame-generating mechanism, aspark-generating mechanism, a resistive heater, or any other suitableheating element. The burner 800 is preferably directed co-directionallywith airflow from the air manifold 410, but can alternatively bedirected against the airflow.

When the biomass thermal conversion system 10 is a gasifier, the systemcan additionally include a reduction zone 500. In these variations ofthe system, the char grinder 100 is preferably arranged in the materialpath between the pyrolysis zone 300 and the reduction zone 500. Thereduction zone 500 is preferably a kinetic bed to better accommodate thecomminuted char, but can alternatively be a fixed bed or any othersuitable bed. By grinding the char into a substantially uniform sizeprior to reduction zone entry and by using a kinetic reduction zone 500,this gasifier confers several advantages over conventional gasifiers.First, this gasifier is capable of accepting, pyrolyzing, and gasifyinga large range of biomass sizes without the issues of char bed packing.Second, the uniform char size created by the char grinder 100 allows forbetter thermodynamics and fluid dynamics within the reduction andcombustion phases.

The kinetic reduction zone 500 of the gasifier functions to gasify thecombusted tar gasses from the combustion zone 400 into gaseous fuel withchar. The reduction zone 500 is preferably a kinetic bed to handle thesmall char particles, and to increase the surface area of the charavailable to gasify the cracked tar gasses. The reduction zone 500 ispreferably fluidly connected to the combustion zone 400, wherein airflowfrom the combustion zone 400 preferably flows combusted tar gas into thereduction zone 500. Airflow from the combustion zone 400 canadditionally move char from the pyrolysis zone 300 into the reductionzone 500, or the reduction zone 500 can be fluidly connected to andreceive char from the pyrolysis zone 300. The received char ispreferably in granulated (post-ground) form. The reduction zone 500 ispreferably substantially continuous with the combustion zone 400 (e.g.,coaxially arranged with the combustion zone 400), but can alternativelybe a separate bed from the combustion zone 400. The reduction zone 500is preferably arranged downstream from the combustion zone 400, but canalternatively be arranged upstream, wherein a casing end or a fixed bed(e.g., the pyrolysis bed) re-routes air from the combustion zone 400into the reduction zone 500.

The reduction zone 500 is preferably heated by waste heat from thecombustion zone 400, but can alternatively be heated by waste heat fromthe power generation system (e.g., engine exhaust or radiator), by aheater, or by any suitable heat. The reduction zone 500 is preferablythermally coupled to and fluidly isolated from the drying module,wherein waste heat from the gaseous fuel dries the wet biomass. Thereduction zone 500 preferably includes a fuel outlet that egressesgaseous fuel, wherein the fuel outlet is preferably controlled andmaintains a fluid impermeable seal within the gasifier. The fuel outletcan include a vent (e.g., a passive one-way vent), an airlock, or anyother suitable mechanism that permits substantially one-way fluid flowtherethrough while maintaining a substantially fluid impermeable seal.However, the fuel outlet can be substantially open.

The simultaneous pyrolysis and communition char grinder 100 functions toreduce a dimension of the solid biomass below a threshold size. Morepreferably the simultaneous pyrolysis and comminution functions to grindchar off the pyrolyzed portions of the solid biomass, wherein the groundchar particles are below a threshold size. The ground char particles arepreferably a substantially uniform size, but can alternatively be arange of sizes smaller than the threshold size. The threshold size ispreferably selected based on the anticipated suspension ability andreaction character in the kinetic reduction zone, but can alternativelybe selected in any other suitable manner. The char grinder 100 includesan abrading body 110 and an abrading cage 130, wherein charring biomassis preferably captured by the abrading cage 130 and is ground againstthe abrading body 110. The ground char preferably passes through thechar grinder 100 into the reaction and/or combustion zone 400, but canalternatively travel along the abrading surface of the abrading body 110and collect at an end of the char grinder 100, wherein said end of thechar grinder 100 is preferably fluidly connected to the reduction zone500, more preferably to the combustion zone 400. Alternatively, theground char can fall past the abrading body 110 and into a collectiondevice for removal from the system such as in a biochar maker or otherpyrolysis-to-charcoal device.

The char grinder 100 is preferably located in the material flow pathbetween the pyrolysis zone 300 and the combustion zone 400, wherein thechar grinder 100 can additionally function to separate the pyrolysiszone 300 from the combustion zone 400. The char grinder 100 canadditionally or alternatively be located between the pyrolysis zone 300and the reduction zone 500. The char grinder 100 preferably formssubstantially the entire interface between the pyrolysis zone 300 andthe combustion and/or reduction zone 500, but can alternatively extendalong a portion of the interface. However, the char grinder 100 can belocated in the body 110 of the pyrolysis zone 300 (e.g., at anintermediate distance between the drying zone 200 and the combustionzone 400) or at any other suitable location within the gasifier. Thechar grinder 100 is preferably arranged with the abrading cage 130proximal the pyrolysis zone 300 and the abrading body 110 proximal thecombustion zone 400 (e.g., proximal the combustion and/or reduction zone500 or distal the pyrolysis zone 300). The abrading cage 130 preferablytranslates (e.g., reciprocates, rotates, etc.) relative to the abradingbody 110, wherein a motor or other translation device preferablycontrols abrading cage translation. The abrading body 110 is preferablystatically coupled to the remainder of the biomass thermal conversionsystem 10, such as to the pyrolysis unit (e.g., welded, screwed, orotherwise mounted to the gasifier body 110), but can alternativelytranslate relative to the reactor body 110, wherein the abrading cage130 is preferably statically coupled to the conversion system. Theabrading cage 130 preferably translates relative to the abrading body110 at a relatively slow speed (e.g., 1-10 RPM), but can alternativelytranslate against the abrading body 110 at any suitable speed. The chargrinder 100 is preferably thermally conductive, and preferably heats thecaptured biomass with heat from the combustion zone 400 and/or reductionzone 500, but can alternatively be thermally insulative, wherein thechar grinder 100 can function to insulate the pyrolysis zone 300 orsubstantially reduce the heat transfer from the combustion zone 400 tothe pyrolysis zone 300.

The abrading body 110 of the char grinder 100 functions to provide asurface that the char can be ground against. The abrading body 110 ispreferably substantially solid and continuous, but can alternativelyinclude through holes (apertures), wherein the abrading body 110functions as a screening device in which the through holes arepreferably substantially equivalent to the desired char particle size.However, the char grinder 100 can include any other suitable screeningdevice that retains the char particle on the side of the char grinder100 proximal the pyrolysis zone 300 until the desired char particle sizeis reached. The desired char particle size is preferably selected basedon the anticipated suspension ability of the reduction zone 500 or thedesired char size as an end product out of the pyrolysis device. Theabrading body 110 preferably includes an abrading surface arrangedadjacent the abrading cage 130. The abrading surface is preferablysubstantially smooth, but can alternatively be textured to facilitategrinding. The abrading surface texture preferably includes raisedsegments extending out of the abrading surface toward the abrading cage130, but can alternatively include recessed segments. The abradingsurface texture can include cross-hatching, raised circular portions,sandpaper, angled teeth, or any other suitable texture. The abradingsurface texture is preferably manufactured as a singular piece with theabrading body 110, but can alternatively be coupled to the abradingsurface after abrading body 110 manufacture (e.g., by adhesion, welding,etc.). The abrading body 110 can be cylindrical, conical, flat (e.g.,prismatic), wavy, or have any other suitable shape. When the abradingbody 110 is curved, the abrading surface is preferably the convex sideof the abrading body 110, but can alternatively be the concave side ofthe abrading body 110.

The abrading cage 130 of the char grinder 100 functions to capturebiomass and to move the biomass against the abrading body 110, morepreferably to grind the char from the biomass against the abrading body110. In operation, the abrading cage 130 grinds the char against theabrading body 110 and against adjacent biomass particles in the vessel.The resistance applied by the abrading body 110, abrading cage 130, andadjacent biomass particles, preferably strips the pyrolyzed portions ofthe biomass off the particle being ground. The form of the abrading cage130 and edges of the abrading cage 130 work to grind the char, as doesthe surface (e.g., broad face) of the abrading body 110. The edges ofthe abrading cage 130 can be substantially dull, but can alternativelybe sharp. The abrading cage 130 preferably includes a singular piecewith a plurality of through-holes, wherein the through-holes arepreferably dimensioned to capture and grind biomass. The through-holescan have a size or dimension selected based on the maximum biomass sizethat the conversion system is configured to receive, the size/dimensionof char that is desired to be passed forward within the system, or canbe based on any other suitable charred biomass parameter. The abradingcage 130 holes can have a circular, polygonal (e.g., regular convexpolygon, concave polygon, rectangular, rhomboid, etc.), or any othersuitable perimeter. The abrading cage 130 can be removably coupled tothe abrading body 110, such that various abrading cages 130 withdifferent hole dimensions can be interchanged. Alternatively, the holedimensions of the abrading cage 130 can be adjustable. Common abradingcage materials include expanded or perforated metal sheet, but theabrading cage 130 can alternatively be made of any suitable material.The abrading cage 130 preferably includes a second abrading surfacearranged adjacent the abrading body 110. The second abrading surface ispreferably substantially smooth, but can alternatively be textured tofacilitate grinding. The second abrading surface texture preferablyincludes raised segments extending out of the abrading surface towardthe abrading body 110, but can alternatively include recessed segments.The second abrading surface texture can include cross-hatching, raisedcircular portions, sandpaper, angled teeth, or any other suitabletexture. The second abrading surface texture preferably complements theabrading surface texture of the abrading body 110, but can alternativelyoppose the abrading surface of the abrading body 110. The secondabrading surface texture is preferably manufactured as a singular piecewith the abrading cage 130, but can alternatively be coupled to theabrading surface after abrading cage manufacture (e.g., by adhesion,welding, etc.). The abrading cage 130 preferably complements the profileof the abrading body 110. More preferably, the abrading cage 130 tracesthe profile of the abrading surface. However, the abrading cage 130 canbe otherwise configured. The abrading cage 130 can be cylindrical,conical, flat (e.g., prismatic), wavy, or have any other suitable shape.When the abrading cage 130 is curved, the second abrading surface ispreferably the concave side of the abrading cage 130 (especially whenthe abrading surface is on the convex side of the abrading body 110),but can alternatively be the concave side of the abrading cage 130. Theabrading cage 130 can translate along the longitudinal axis of theabrading body 110, but can alternatively translate perpendicular to thelongitudinal axis of the abrading body 110, translate in an arcuatedirection about the abrading body 110 (e.g., roll about the abradingbody 110), or translate in any suitable manner relative to the abradingbody 110.

2. Examples of Biomass Thermal Conversion Systems Including the CharGrinder

In a first example of the biomass thermal conversion system 10 as shownin FIG. 1, the biomass thermal conversion system 10 is a horizontalpyrolysis retort reactor, wherein the combustion zone 400 is surroundedby the pyrolysis zone 300 and the char grinder 100 substantiallysurrounds the combustion zone 400, separating the combustion zone 400from the pyrolysis zone 300. The pyrolysis zone 300 is preferablydefined by a casing 900, wherein the casing 900 additionally includes aretort tube 910 that is substantially sealed from and surrounded by thebiomass material under pyrolysis. Combustion preferably occurs withinthe retort tube. The casing 900 preferably additionally defines thedrying module, such that the drying stage and pyrolysis stage are mixedwithin a single module. However, the pyrolysis stage can be fed by adrying module separate from the casing 900. The combustion zone 400 ispreferably arranged at a second end of the casing 900, distal andopposing the first end of the casing 900. The first end of the casing900 preferably opposes the second end of the casing 900 along a gravityvector, wherein the second end of the casing 900 is preferably lowerthan the first end. The combustion zone 400 preferably extends along thelength of the second end of the casing 900, but can alternatively extendalong a portion of the second end of the casing 900, extend at an angleto the second end of the casing 900, or extend in any suitablearrangement relative to the second end of the casing 900. The combustionzone 400 can additionally extend along the width of the casing 900 oralong a portion of the casing width. The combustion zone 400 ispreferably separated from the second end of the casing 900 by acollection area, wherein char preferably flows around the retort tube,around and through the char grinder 100 into the collection area. Thesecond end of the casing 900 can additionally include a chartransportation mechanism (e.g., an auger) that moves the comminuted charto the char outlet. Alternatively, the second end of the casing 900 canbe removable from the body 110 of the casing 900, such that biochar canbe collected from the collection area. The combustion zone 400 canadditionally separate the collection area from the pyrolysis zone 300.The combustion zone 400 is preferably proximal a first side of thecasing 900 (preferably normal to the second end of the casing 900, butalternatively otherwise arranged), wherein the first side of the casing900 preferably includes an air manifold 410 fluidly connected to anoxygen source (e.g., an oxygen tank or ambient environment), a tar gasmanifold 430 fluidly connected proximal the first end of the casing 900,and a burner 800 located at the end of the air manifold 410 within thecasing 900. The char grinder 100 preferably encircles the retort tube910, but can alternatively trace a portion of the retort tube 910. Thechar grinder 100 preferably includes a substantially solid abrading body110, wherein the char ground at the interface between the pyrolysis zone300 and the combustion zone 400 flows around the combustion zone 400into the collection area. The abrading cage 130 is preferably rotatedabout a longitudinal axis of the abrading body 110 by a motor or anyother suitable translation device, preferably at 1-10 rpm butalternatively faster or slower. However, the abrading cage 130 cantranslate in any suitable manner relative to the abrading body 110.

In a second example of the biomass thermal conversion system 10 as shownin FIG. 2, the biomass thermal conversion system 10 is a slantedpyrolysis retort reactor, wherein the retort tube 910 extends at anangle to a gravity vector along a first end of a casing 900 defining apyrolysis zone 300. The first end of the casing 900 can additionallyfunction as a first side of the retort tube 910 defining the combustionzone 400. The first end of the casing 900 preferably additionallyfunctions as a thermal interface between the pyrolysis zone 300 and thecombustion zone 400. The char grinder 100 is preferably located alongthe first end of the casing 900. The abrading cage 130 of the chargrinder 100 preferably traces the first end of the casing 900, and ispreferably a substantially flat plate but can alternatively be a curvedplate or have any other suitable geometry. The first end of the casing900 preferably functions as the abrading body 110. The abrading cage 130is preferably reciprocated along a longitudinal axis of the first end ofthe casing 900 by a motor or any other suitable translation device,preferably at 1-10 rpm but alternatively faster or slower. However, theabrading cage 130 can translate in any suitable manner relative to thefirst end of the casing 900. The first end of the casing 900 can beperforated and fluidly connect the chamber defining the combustion zone400 with the pyrolysis zone 300, wherein char falls down the angledslope and can be collected through the char outlet. The first end of thecasing 900 can be perforated along its entire length, or can beperforated along a portion of its length. Alternatively, the first endcan be substantially solid and continuous, wherein ground charpreferably collects at the lower end of the pyrolysis zone 300 and canbe removed from the system through a char outlet. The chamber preferablyincludes a biomass inlet 210 that receives fuel from a drying modulelocated on the second end of the casing 900, wherein the second end ofthe casing 900 preferably opposes the first end of the casing 900 (e.g.at the top of the chamber). The chamber preferably includes an airmanifold 410 fluidly connected to a first end of the chamber distal thebiomass inlet 210. The first end of the chamber and/or the air manifold410 can be fluidly connected to the pyrolysis zone 300 proximal thesecond end of the casing 900 by a tar gas manifold 430, wherein the targas manifold 430 transfers tar gas created during pyrolysis to thecombustion zone 400. The first end of the casing 900 additionallyincludes a burner 800 that combusts the injected air and tar gas. Thechamber preferably additionally includes a char outlet at the lowestpoint of the gravity vector, although the char outlet can be located atany other suitable position.

In a third example of the biomass thermal conversion system 10 as shownin FIG. 3, the biomass thermal conversion system 10 is a hybrid fixedkinetic gasifier, wherein the drying zone 200 and pyrolysis zone 300 arelocated within a fixed bed, and the combustion zone 400 and reductionzone 500 are located within a kinetic bed. The fixed bed preferablysurrounds the kinetic bed, but can alternatively be surrounded by thekinetic bed. The gasifier is preferably arranged with a longitudinalaxis parallel to a gravity vector, wherein the drying zone 200 ispreferably arranged above the pyrolysis module. However, the gasifiercan be arranged horizontally or at any suitable angle relative to agravity vector. The char grinder 100 preferably separates the pyrolysiszone 300 from the combustion zone 400 and reduction zone 500. The chargrinder 100 preferably encircles the combustion zone 400 and reductionzone 500, wherein the air manifold 410 preferably extends within ordirects air into the lumen defined by the char grinder 100. However, thechar grinder 100 can be otherwise oriented. The char grinder 100preferably includes a perforated abrading body 110 such that only groundchar and tar gasses can enter the combustion zone 400, and subsequently,the reduction zone 500. The abrading body 110 is preferably a separatepiece from the chamber defining the reduction zone 500, but canalternatively be a portion of the chamber, be a continuation of thechamber, be fixed to the chamber, extend from an end of the casingproximal the combustion chamber, or be otherwise arranged within thereactor. The abrading cage 130 preferably rotates about the abradingbody 110, but can alternatively slide linearly along a longitudinal axisof the abrading body 110 or otherwise translate relative to the abradingbody 110. The abrading cage translation is preferably driven by a motoror any other suitable translation mechanism, and preferably translatesat a rate of 1-10 rpm but can alternatively translate faster or slower.

The kinetic bed of the hybrid gasifier can be a fluidized bed (e.g., asshown in FIG. 3), a swirl or cyclonic bed (e.g., as shown in FIGS. 4 and5), a centrifugal bed, or any other suitable kinetic bed. The combustionairflow is preferably directed upward (e.g., against the gravityvector), such that the reduction zone 500 is arranged upstream and abovethe combustion airflow. However, the combustion airflow canalternatively be directed in any other suitable direction, wherein thecombustion airflow is preferably directed toward the reduction zone 500.The combustion zone 400 is preferably arranged adjacent the lowerportion of the pyrolysis zone 300, wherein the combustion zone 400 isdefined downstream from the air manifold termination. The air manifold410 feeding the combustion zone 400 can direct combusting gasses and/orbiomass toward the reduction zone 500, or can direct combusting gassesand/or biomass from the reduction zone 500 (e.g., along a gravityvector), wherein the casing defining the fixed bed and/or the fixed bedturns and redirects the combusted gasses toward the reduction zone 500.The gas flow within the combustion zone 400 can be linear, rotational,or have any suitable flow pattern. The combustion zone 400 preferablyadditionally includes a burner 800 at the air outlet 413 of the airmanifold 410 that heats the air and tar gasses to combustiontemperatures. The combustion zone 400 is preferably substantiallymaterially isolated but fluidly connected to the pyrolysis zone 300, butcan alternatively be materially continuous with the pyrolysis zone 300.The reduction zone 500 is preferably a kinetic bed as well, and can be afluidized bed (e.g., as shown in FIG. 3), a cyclonic bed (e.g., as shownin FIGS. 4 and 5), a centrifugal bed, or any other suitable kinetic bed.In some variations of the gasifier, the reduction zone 500 canadditionally include a particulate separation mechanism 510. Theparticulate separation mechanism 510 is preferably a rotary blower 511with vanes 513 that collect and bias char particulates against the wallsdefining the reduction zone 500 (e.g., as shown in FIGS. 4 and 5), butcan additionally or alternatively include vanes extending from saidwalls that guide char back toward the combustion zone 400, baffle platesthat create a tortuous flow path that collect the char, or any othersuitable particulate separation mechanism 510. The particulateseparation mechanism 510 can additionally control the flow patternswithin the reduction zone 500. The reduction zone 500 is preferablysubstantially separate from the combustion zone 400.

In one variation of a gasifier having a cyclonic bed as shown in FIG. 4,the reduction zone 500 is separated from the combustion zone 400 by acone, In this variation, the combined swirl flow of the combustion zone400 and the rotary blower creates a spouted vortex kinetic bed. Char iscomminuted as biomass is forced against the char grinder 100, and fallsdown into the second closed end of the casing defining the gasifier.Comminuted char is pulled into the reduction zone 500 by the cyclonicairflow stemming from the combustion zone 400 and reduction zone gasflow, spins outward onto the reduction zone walls, and is directed backdownward into the cone by the rotary blower, in combination with thespiral directing vanes on the walls of the reduction riser. Subsequentairflow from the combustion zone 400 into the reduction zone 500 createsa spouted vortex 550 out of this collected bed in the cone. The gasifiercan additionally include a char removal mechanism 700 arranged below orproximal the center channel that removes char prior to char entry intothe reaction zone for an external use (such as biochar). The charremoval mechanism 700 preferably includes a char collector thatfunctions to retain the char within or removed from the gasifier. Thechar collector is preferably arranged below the grinding mechanism alonga gravity vector, but can alternatively be arranged at any othersuitable location relative to the gasifier. The char collector ispreferably mounted to the gasifier, but can alternatively be removablycoupled to the gasifier or distal the gasifier. The char removalmechanism 700 can additionally include a char transportation mechanism,such as an auger, belt, conveyor, or any other suitable transportationmechanism that transports char from the char collector or any othersuitable portion of the gasifier to a secondary container distal thegasifier.

In another variation of the gasifier as shown in FIG. 5, the hybridgasifier is a cyclonic gasifier that is oriented at an angle to agravity vector, more preferably oriented perpendicular (e.g.,horizontal) to the gravity vector. The gasifier includes a casing 900, achannel arranged coaxially within the casing 900 and extendinghorizontally along a portion of the casing width from the first end ofthe casing 900, a combustion container arranged in the end of thechannel proximal the second end of the casing 900, a first air manifold410 that introduces air into the combustion chamber, and a flue gasmanifold extending from the combustion container, more preferably alongthe channel length toward the first end of the casing 900. The channelinterior is preferably fluidly connected to the space between thechannel and the casing 900. The first air manifold 410 is preferablyangled relative to the channel longitudinal axis, and preferablyintroduces air tangentially into the combustion chamber such that arotary flow is induced. The gasifier can additionally include aparticulate separation mechanism 510, such as a rotary blower, arrangedwithin the first end of the channel, wherein the rotary blower recycleschar toward the second fluid manifold inlet within the channel interior.The gasifier can additionally include a tar recycling manifold 430fluidly connecting a portion of the casing 900 above the channel (e.g.,along a gravity vector) to the combustion container. The gasifier canadditionally include a char grinder 100 encircling the channel forin-situ size reduction of feedstock, wherein the char grinder 100 ispreferably driven by a motor. The reduction zone 500 is fluidlyconnected to and receives comminuted char from the char grinder 100,wherein the char preferably flows through the char grinder 100 and intothe reaction zone. Alternatively, the granulated char can flow aroundthe char grinder 100 into a collection zone. The gasifier canadditionally include a char removal mechanism arranged below thechannel, so as to remove char before it enters the reaction zone, for anexternal use (such as biochar). The gasifier can additionally include anindirect gasification mechanism that functions to remove combusted targas from the gasifier prior to reduction, and to use the heat from thecombusted tar gas to heat a second fluid stream (usually steam) that isused to reduce the char into fuel. Indirect gasification is achieved bythe following combination of elements. A combustion container fluidlyseparates the combustion zone 400 from the reduction zone 500, with thecombustion container arranged within the end of the channel proximal thesecond closed end of the casing 900. The combustion container can bestatic or mobile. The combustion container is preferably arranged withinthe channel such that a char inlet is created between the channel andthe combustion container (e.g., the channel interior is fluidlyconnected to the pyrolysis zone 300). The combustion containerpreferably has an outlet fluidly connected to a flue gas manifold. Theflue gas manifold is preferably thermally connected to a second fluidmanifold. The second fluid manifold is preferably fluidly connected tothe channel interior (e.g., the reduction zone 500). The second fluidmanifold can only transfer the second fluid or can transfer the secondfluid and an oxygen-laden fluid source (e.g., ambient air). The secondfluid manifold and flue gas manifold are preferably arranged such thatcross-flow is induced between the respectively contained fluids, but canbe alternatively arranged. In operation, tar gas is extracted from thegasifier (e.g., from a point above the pyrolysis zone 300, relative to agravity vector) and fed into the combustion container. The tar gas iscombusted within the combustion container and the resultant gas flowsinto the flue gas manifold, wherein the flue gas exchanges heat with theincoming second fluid (e.g., steam). The waste heat from the flue gascan additionally function to heat the pyrolysis zone 300. The secondfluid flows into the reduction zone 500 (e.g., channel interior) and isreduced into gaseous fuel, which preferably subsequently flows out ofthe gasifier through a fuel outlet 610. This indirect gasificationmethod enables the gasifier to run in a variety of modes, from fullsyngas output without nitrogen dilution, to mixed char and gas output,to full char output by means of operating the gasifier as a pyrolysisretort.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

I claim:
 1. A biomass thermal conversion system comprising: a fixed beddrying zone; a fixed bed pyrolysis zone fluidly connected to the dryingzone; a combustion zone fluidly connected to the pyrolysis zone by amaterial path; and a comminution mechanism arranged across the materialpath between the pyrolysis zone and the combustion zone, configured togrind char off a pyrolyzed surface of solid biomass and reduce adimension of the solid biomass below a threshold size.
 2. The system ofclaim 1, wherein the pyrolysis zone is fluidly connected to thecombustion zone at an interface, wherein the comminution mechanismcomprises the entirety of the interface.
 3. The system of claim 2,wherein the comminution mechanism encircles the combustion zone.
 4. Thesystem of claim 3, further comprising a casing comprising a solidmaterial inlet, the casing defining the drying zone proximal the solidmaterial inlet and defining the pyrolysis zone distal the solid materialinlet across the drying zone, wherein the grinding mechanism defines thecombustion zone, wherein the pyrolysis zone abuts against thecomminution mechanism.
 5. The system of claim 4, wherein the pyrolysiszone surrounds the comminution mechanism.
 6. The system of claim 4,further comprising an insert extending through the drying and pyrolysiszones and fluidly connected to the combustion zone, the insert defininga reduction zone.
 7. The system of claim 4, further comprising a chartransportation mechanism distal the solid material inlet proximal thecomminution mechanism and arranged below the comminution mechanism alonga gravity vector, the char transportation mechanism fluidly connected toa char collection mechanism.
 8. The system of claim 1, wherein thecomminution mechanism comprises an abrading body and an abrading cage,wherein the abrading cage is configured to translate along a broad faceof the abrading body.
 9. The system of claim 8, wherein the abradingbody is solid and continuous.
 10. The system of claim 8, wherein thebroad face comprises an abrading textured surface.
 11. The system ofclaim 8, wherein the abrading cage comprises retention featuresconfigured to retain pyrolyzed material having a dimension larger thanthe threshold size.
 12. The system of claim 11, wherein the retentionfeatures comprise apertures through a thickness of the abrading cage.13. The system of claim 8, wherein the grinding mechanism furthercomprises a motor operatively connected to the abrading cage, the motorconfigured to translate the abrading cage relative to the abrading body.14. A method for thermal conversion of solid biomass, comprising:providing a gasifier defining a fluidly continuous drying zone,pyrolysis zone, and combustion zone; drying the solid biomass with thegasifier within the drying zone with waste heat from the pyrolysis zone;pyrolyzing dried solid biomass with the gasifier within the pyrolysiszone with waste heat from the combustion zone; grinding pyrolyzedportions off solid biomass in situ in the pyrolysis zone with a grindingmechanism to normalize the pyrolyzed solid biomass to a dimensionsmaller than a threshold size; and combusting the comminuted solidbiomass into combustion products.
 15. The method of claim 14, furthercomprising reducing the combustion products.
 16. The method of claim 14,further comprising collecting the ground solid biomass with a charcollector arranged below the grinding mechanism along a gravity vector.17. The method of claim 16, further comprising transporting the groundsolid biomass from the char collector to a secondary container distalthe gasifier.
 18. The method of claim 14, wherein grinding pyrolyzedsolid biomass in situ comprises: retaining pyrolyzed solid biomass withan abrading cage; grinding pyrolyzed material off the solid biomass bytranslating the abrading cage retaining the pyrolyzed solid biomassalong a broad face of an abrading body.
 19. The method of claim 18,further comprising selecting for ground pyrolyzed material having adimension smaller than the threshold size with an aperture through theabrading body having a width equal to the threshold size.
 20. The methodof claim 18, wherein translating the abrading cage along a broad face ofan abrading body comprises rotating the abrading cage about alongitudinal axis of the abrading body.